Bioavailability of lab-contaminated and native polycyclic aromatic hydrocarbons to the amphipod Corophium volutator relates to chemical desorption

In the present study, the relationship between bioavailability of polycycli c aromatic hydrocarbons (PAHs) to benthic amphipods and the PAH desorption kinetics was examined. To that end, field-contaminated sediment was treated in three different ways. One subsample had no addition of PAHs and contain ed native PAHs only. To a second subsample, six PAHs (phenanthrene, fluoran thene, anthracene, pyrene, benzo[b]fluoranthene, and benzo[k]fluoranthene w ere added in the laboratory. Two of the PAHs were added at higher concentra tions to a third subsample, serving as a control for concentration-dependen t uptake. Marine amphipods (Corophium volutator) were exposed to the three subsamples for a maximum of 25 d and were subsequently analyzed. Desorption kinetics were determined for both the lab-contaminated and the native PAHs . The biota-to-sediment accumulation factor (BSAF) values of the individual native and lab-contaminated PAHs correlated well with the rapidly desorbin g fraction (R-2 = 0.76). The BSAFs were 1.4 to 3.3 higher for the lab-conta minated PAHs compared with the native PAHs, while the difference between th e rapidly desorbing fractions was a factor of 1.1 to 1.8. The BSAFs of the lab-contaminated PAHs in the second and third subsample were equal, indicat ing concentration-independent accumulation. The results suggest that lab-co ntaminated PAHs are more available to amphipods than native PAHs and that d ifferences in bioavailability of lab-contaminated and native PAHs to marine amphipods are related to differences in desorption behavior.